Families constituting the Order Passeres. 415 



the whole series. This bond of union, I maintain, is found 

 in the total abortion of the first primary quill ; and although 

 in the case of some of the families we may not see any other 

 charaeter to unite them, this should not militate against giving 

 due weight to a structural peeuliarity which is found to be 

 absolutely constant throughout all the species of several ex- 

 tensive families, and to confirm, in many cases, the conclu- 

 sions which ornithologists have arrived at from other cha- 

 racters. It is therefore the separation of the families con- 

 stituting the " Tanagroid Passeres " as a distinct group which 

 forms the main feature of my proposed arrangement, and in 

 which its chief value (if any) is to be found. 



As it is not always possible to determine the number of the 

 primary quills without injuring the specimen, and not pos- 

 sessing duplicates of many of the requisite forms, I have in 

 general taken the statements of Professor Sundevall to be cor- 

 rect. He has devoted himself for many years to the special 

 study of the details of external form and structure in birds, 

 and in the work already quoted has, in most cases, given the 

 number of the primaries and the nature of the first quill. 

 But (as I think, very unfortunately) he has only occasionally 

 given weight to this character in his classification, which de- 

 pends mainly on the varieties of scutellation of the tarsi. 

 This latter character can hardly have the high value he giA'cs 

 it, since it leads to such unnatui'al combinations as Larks 

 and Hoopoes, Todus and Pipra, Irrisor and Epiniachus — 

 errors due in great part to his refusal to give any weight to 

 purely anatomical characters. Yet in many respects his clas- 

 sification is a great advance on most of those which have 

 preceded it, since it defines every group by clear external cha- 

 racters, which, if not always of the value he assigns to them, 

 will be of great service to future workers at the classification 

 of birds. 



The foregoing systematic sketch has been arrived at after 

 often renewed attempts at a natural arrangement of Passeres, 

 for the piu'poses of a work, on the Geographical Distribution 

 of Animals, on which I have been some time engaged. The 

 conclusions now set forth seem to me more satisfactory than 



